Electric separator.



H. A. WENTWORTH.

ELECTRIC SEPARATOR.

APPLICATION FILED FEB.. 3, 190s.

yPatented sept. 22, um

UNITED STATES PATENT oni-uen.

HENRY AZOR WENTWORTH, OF LYNN, MASSACHUSETTS, ASSIGNOR TO HUFF ELECTRO- .STATIC SEPARATOR COMPANY, OF BOSTON, MASSACHUSETTS, A- CORPORATION OF MAINE.

ELEc'rRrc surname.

Patented Sept. 22, v1908.

Application led February 3, 1908. Serial No. 413,999.

To all 'whom it may concern:

Be it known that I HENRY AzoR WENT- WoR'rH, a citizen of the United States, and resident of Lynn, in the county of Essex and State of Massachusetts, have invented new and useful ,Im rovements in Electric Separators, of whic the following' is a specification.

My invention relates to apparatus for electrical separation of dierent com onents of mixed comminuted solid material) and consists in improvements in such apparatus presently to be described.

In Patent No. 801,380 dated the 10th day of Oct. 1905, issued to Charles H.- Huff, there is described4 an electrical apparatus in which vone structural feature'consists in an electrode composed of a wire entirely surrounded by a dielectric envelop, more specificall a metal wire drawn through a relatively 't ick glass tube. When the electrical apparatus is excited from a source of varying potential, aI concentrated and effective field is established between the insulated velectrode and the uninsulated electrode, and, so far as I am aware,

rapidly varyin situations where the field is ing, the structure described in the'said Huff a patent serves its purpose admirably. The

4is tat the iversity of materials. which it is desirable to treat separatively by electrical means is so great that, although the separative process.

employing brief intermittent potential (as described in Patent N o. 805,694, dated Nov. l

28, 1905 to Philip H. V`Wynne)`, is effective o ver a very large range `and variety of materials, nevertheless, some mixtures of mater1al have been encountered which, while re-l s o nsiveto electrical' separation under con-l itlons of intermittent and alternating potenti'al, may be more effectively treated under conditions of steady-and unidirectional electric charge. Treatment of some mixtures by electrical separation employing a tential,-sometimes in itself is sufficient to effect a commercially acceptable se aration or concentration and sometimes is o value asf a` preparatory or supplementary adjunct to the electrical-separation `characterized by conditions of internittentT-and p alternating potential. A 'diliicu ty which oftenj attended the em loyment of steady` ersistence of the charge, when the potentia is' raised, produces disruptive discharges'unless adeguate means are proy drical drum electrode unidirectional charge vided to prevent them. The surrounding of one of the electrodes, asin the said Huff patent, by a continuous dielectric envelop while effective to prevent disruptivedischarge introduces another detrimental phenomenon in the operationof the separator when steady or unidirectional potential is employed.

My invention herein to be described consists of new factors in electrostatic separation apparatus by which unidirectional charges at high otential and of substantially continuous character may be employed without involving the detrimental incidents heretofore observed.

In the drawings hereto annexed which illustrate' embodiments of my invention,- Figure 1 is a fragmentary illustration in pers ective showing a ortion of the apparatus escribed in the" said) Huff patent; Fig. 2 is a fragmentary illustration of an apparatus which embodies features of my present improvement; Fig. 3 is a detail on an enlarged scale in cross section showing an electrode and its insulating' su port; Fig. 4 is a diagram illustrating an e ectrical generating apparatus for an electrostatic separator Fig. 5 shows in diagram the characterof the p0- tential wave form produced by the apparatus of Figl; Fig. 6 is a diagram showing a modified wave form such as is produced by the employment of my improvements; Fig. 7 is a diagram showing the fundamental elements of an electrical separation apparatus Acontaining my improvements and Fig. 8 is a fragmentary view of an electrical separation apparatus which embodies my invention in a modified form.

In Fig. 1 which shows a portion of the apparatus described in the laforesaid Huff patent (which may be referred to, to supply details not herein shown) E is a portion of a cylinlectively the structure of the opposed electrode, wherein e is a-metal wire and G is a .glass tubeinclosing the Wire. When the charge upon thc wire c is unidirectional'and and E designates col- Athe potential employed is sufficiently high I to cause a repulsion of electro conductivel particles from the surface of the electrode E, many of-these particles, especially the very fine dust, will be carried into contact with the Asurface g of the dielectric envelop G and will clin theretojeventu'ally, in the operation pf t e machine, coating the tube -G with a superficial film of closely packed conductive- Ivface of the wire e on the one hand, and the trode.

film of the conductive particles on the tube G, on the other hand, supplying the conductive surfaces, andthe glass or other dielectric material of the 'tube G constituting the dielectric which Separates the two conductive surfaces. This condition of course destroys the effectiveness of the electrostatic field between the two electrodes E EX and vitiates the performance of the apparatus.

Even where there is no quantity of dust to actually stick to the electrode or other dielectric envelop, there is a slight electrical discharge from the metal cylinder to the surface of the glass, which after a short period of excitation carries sufficient charge through the air to the surface of the glass to give the condenser effect and thus vitiate the action of the machine.

In Fig. 2 there is illustrated in part an apparatus, by the aid of which unldirectional and, if desired, substantially constant high potentials may be employed without incurring the disadvantages due either to disruptive discharge or tothe above described condenser effect. As in Fig. l, E represents a portion of a metallic cylindrical drum elec- The op osed electrode represented collectively by lil consists of a metallic portion e shown as a wire, and a barrier F, composed` of low conductive material, as wood or fiber, the whole or part of which shouldA he of sufficiently effective insulating material so as to prevent disruptive dischar e from the surface of wire el directly to the e ectrode vE and yet should be capable of allowing an electric charge to cree over it. The wire e 1s partiall surrounde by a barrier F which in effect ies between the drum -E and the wire e. In the form shown in Fig.'2 the partial envelop .or barrier F consists of low conductive material U-sha ed `in cross-sec# tion, the wire e lying at t e bottom of the 'groove f3 which is flanked on either side by the wings f. The bottom of the U at f stands between the wire e and the electrode E. In Fig. 3 the construction of the electrode E is shown on a larger scale. If the F is composed in itself will stand a hig disruptive voltage, the wire e may be laid in contact with the envelop vF at the bottom of the groove fs. sulation is desired, a sheet or sheets of better insulating material suchas oiled cambric, nrlajy2 be laid inthe groove Fa as a lining, as a The precise shape of the ybarrier or envelop F is by no meansessential; there is shown in Fig. 8 a form consisting of a flat stri to the back of which the wire e is secure ;in the instance shown, the wire rests upon the ledge f4. The effect of the above described struc- If, however, a more effective inture is as follows: When theelectrode wire is connected to a source of unidirectional electric charge, the charge creeps over the surface of the barrier F around the wings f to .the portion at f which is presented in op osition to the surface of the electrode E. he field is, established as between the surface at f and the electrode E, and is maintained by the flow of charge from the wire e over the surface of the barrier at F. As the surface presented to the electrodeE is low-conductive material, the danger of -disruptive discharge is minimized. The possibility of such discharge from the metal surface of the wire e is effectively reduced because the. path of 80 such discharge would have to be from the wire e around the barrier F and thence to the electrode E. This creeping charge over the barrier F immediately neutralizes the small but cumulative charges brought over by the re elled material from the op osite electrode, or y the sli ht electrical disc arge. Whereas with the uff glass electrode `of non conducting material, which was used merely to prevent disruptive discharge or to concentrate the field, a very thin layer of mineral dust re elled across and adhering thereto, effectualfly reduced the efficiency of the action of the machine, with my new form of apparatus this dust may accumulate` upon the barrier to a thickness of inch ormore without im airing the action of the machine. In practica field use of the machine, this is av very important feature. 1

'A preferable mode of obtaining electric charge or high potential is to employ an aparatus such as is illustrated in Flg. 4; `there E represent the electrodes of a separator; the rima source of energy is represented at whic may be an alternating current dynamo. The current goes to a step-up transformer T T, one terminal of which 1s connected through a rectifier R to one electrode, as E', the other, terminal of the coil T goes to the op osite electrode through the 110 spark gap S. he effect at the electrodes of t e apparatus shown Fig. 4 is diagrammat- (i ically shown in Fig. 5, Where o-o represents the zero line of potential and the curve 'the curve of alternating. otential of the gen- 115 erator D. The potentia represented by the line rises to the breaking point of the spark gap when the spark gap breaks, the electrodes E E are connected with the source and their potential rises. The presence of a 120 rectifier R cuts out, We`will say, the charge representedby the lower crests 'n of the otential curve so that-the potential at the efectrodes is repriesented by the curve p-n/. This method of obtaining high tension charge 1 25 gives a series ofsmall impulses which last only so long as the exciting force is acting.

' But if steady potentials are to be used, the

more nearly steady the conditions can be maintained, themore nearly uniform is the action ofthe separator. If nowuthe arrangement illustrated in Figs. 2, 3, and 8 be employed the curve of potential on,the electrode wire e is such as represented by theline p-n of Fig. 5. At each accession of potential the charge iiows from thewire e over the surface of the barrier F, distributing itself more and more evenly as it recedes from the wire e so that the curve of potential at the portion f of the barrier F, while doubtless subject to some fluctuations, is represented ualitatively by the modiiied Wave shown by t e line p2 of F1g.y6. The surface of thebarrier F servesv as a reservoir to equalize the intensity of iield between the portion f of the electrode E and the electrode E.

In Fig. 7 there is illustrated diagrammatically the essential operative elements of an electrostatic separator such as is above described, wherein Xf represents, conventionally, the generative apparatus E E the two electrodes, H a ho per to deliver materialto the electrode ls (which rotates in the direction of the arrow shown), F is a divider or screen to maintain the se aration electrically roduced between repe ed particles as at brush which may be used to remove from the electrode Ev any particles which may clingthereto.

What I claim and'. desire to secure byLetters Patent is: j

T. In an electrical separator, the combination of a pair of electrodes, a barrier of low conductive material between the electrodes, close to and partly surroundingone ofthe electrodes, means to su ply material to the other' electrode, means? unidirectional char e to the shielde electrode, and means or separately collecting electrically separated components of the material.

2. In an electrical separator, the come bination of a pair of electrodes, a barrier between the electrodes close to and eXtend-A and others as at M, B 1s a.

or sup lying tric charge thereto in intermittent unidirectionaly impulses, ,and a reservoir of electric charge in close proximity to one of the electrodes consisting of material of low conductivity.

r 4. In an electrical se 'araton the combination of electrodes, a arr'ler of low conductive material between the electrodes, and

or sup lying unidirectional close to and partially surrounding one elec trode, ineans to supply material to theother electrode, means or maintaining substantially persistent unidirectional electric charge on the shielded electrode, andmeans for separately collecting electrically separated components of the material.

5. In an electrical separator, the combination of a material-receiving electrode, an opposite electrode comprising a conductive member and a low conductive barrier partially surrounding thesame, means to supply unidirectional intermittent electric charge tothe said conductive member, and means for separately collecting electrically separated components of the material.

6. In an electrical` separator, the combination Iof a I air of electrodes, means to supply materia thereto, a reservoir of charge,

composed of low-conductive material, in

close proximity to one of the electrodes and shielding it from the other electrode. v

Signed b me atBoston', Massachusetts, this thirtiet day of January, 1908.

HENRY AZOR WENTWORTI-I. Witnesses:

CHARLES D. WoonBERRY, JosEPHINE H. RYAN. P. 

